So the winter has been time for a full teardown to mount the new seat, and a few other changes came along too, which will probably drag into the spring!

Before the teardown, I mounted the charger on-board and used this panel connector in the tank where the filler was:

When she was stripped I made this subframe for the seat.

I still have to make a filler panel for the cutout in the rear of the tank from the old seat. the tail light will go on a fender out the back of the seat.

I 'came into' a ZX-12R front end and VFR750 swingarm as well. the front end is there to stay, and I'm 90% on keeping the swingarm. I was worried about the rear sprocket size (because the max size is constrained by the shape of the swingarm), but I've realised the fix for that is to go for a smaller pitch chain, like 420 or 428. Then I can fit 60t on the rear no problem, maybe even 65t. The current struggle is the shock linkage, because the VFR750 shock is so long there's noting to mount it to at the top. Some more research/work to be done there, but I'm sure it'll work out.